Dirt. It seems so simple. The foundation on which we grow, feed ourselves, build from and even walk on. Dirt is something we take for granted. But really, it’s very complex. There are different types of dirt. Bedrock, top soil, loam, silt…..  Farmers, scientists, and microbiologists  have been working with and studying dirt for many years. 

As vegetable growers, we want to create the best dirt, or soil, we can for growing vegetables in. So, what does that mean? Well, there really isn’t one answer. But through observation, testing and amendments, we can come to an educated conclusion. There are a few things we need to know about soil health first. Soil is a combination of clay, silt, sand, and organic material to form the texture. It also contains minerals, nutrients and microbes needed to help plants grow. Here, we will examine how to amend your soil’s texture. 

Clay, silt, sand and organic matter make up soil’s texture and ability to retain water and air. Soil particles that are very small, like clay, retain a lot of water while soil particles that are larger, like sand, allow water to run through quickly. As a grower, you want to balance this out, allowing for just enough water to get to the roots of your plants, but still having enough drainage your plant’s roots won’t rot. Organic matter, like compost or deteriorating leaves or plants, help your soil’s texture by aerating it, giving roots the room they need to grow, but storing some of the moisture so your plants can use it later. Too much of any one can result in poor root or leaf development or poor germination (the process seeds go through to start growing). 

Reading your soil texture

There are several ways you can read the texture of your soil. One quick way is to make a shallow impression in your garden about 2 inches deep, like a shallow bowl. Fill it with water. If the water filters through and your soil is dry in 30 minutes to an hour, you may have sandier soil. If there is still standing water after 30 minutes, you may have heavier clay soil. If it filters through, but is still damp an inch down after 30 minutes, you likely have a good balance. 

Another way is to perform a jar soil test. Fill a quart jar 2/3rds of the way with soil from your garden. Add enough water to saturate the soil and fill the jar the rest of the way. Shake the jar a little and leave it in an out of the way place, undisturbed for a couple days. The soil will settle into layers of sand, silt, clay and organics. 

How to amend your soil

Adding amendments like compost, peat moss, vermiculite, or well rotted manure can help improve your soil structure and give your plants the air and water they need to grow. To amend your soil on a boulevard, first rake back any mulch left from last season. Next, remove a little of the soil that is already there. You don’t want the soil level to be over the curb. Keeping your soil curb level or a little lower will prevent runoff and keep all that precious topsoil you worked so hard on from washing down the sewer. Once you’ve removed a little of the existing soil, spread a layer of your amendments over your garden. How much you need depends on how much you want to alter, but generally, 2 cubic feet or 2 bags of compost is enough for an 11’x5’ Tiny Field. Work the amendments into the top foot of soil by either working it with your hands, or turning the soil over with a shovel.

If you have sandy soil: Amend your soil with compost or peat moss

If you have heavy clay soil: Amending can be more difficult. Amend with compost and ground up leaves. Be careful not to over work clay soil. Never add sand. 

If you have a good balance: Congratulations!!! No need to alter anything. 

Consider a cover crop in the fall. 

Cover crops are a specific plant planted primarily to benefit the soil and not for harvesting. There are several ways to utilize cover crops. Some farmers turn them into the soil shortly after they start growing. Some farmers leave cover crops all year to hold the soil between rows of harvest crops. In a Tiny Field, planting field peas as a cover crop in the fall is a great way to improve texture and fix nitrogen to your soil.  They will grow in the spring, reach maturity and die back just as it’s time to start planting. Their root system will hold soil in place and feed the soil as they die off. 

This is my first year gardening. This seems really complicated. Do I have to amend my soil? Good soil quality is key to growing as much produce as you can and I recommend it. But unless your soil is in terrible shape, you do not have to amend your soil. With annual vegetables, somes it’s best to grow a year and see what happens. Make good observations when you water. Take note of how your soil changes after you work in it. It’s ok to make the changes you think you need next season.